Time Dependence of Plasma Malondialdehyde, Oxypurines, and Nucleosides during Incomplete Cerebral Ischemia in the Rat

Abstract

Incomplete cerebral ischemia (30 min) was induced in the rat by bilaterally clamping the common carotid arteries. Peripheral venous blood samples were withdrawn from the femoral vein four times (once every 5 min) before ischemia (0 time) and 5, 15, and 30 min after ischemia. Plasma extracts were analyzed by a highly sensitive high-performance liquid chromatographic method for the direct determination of malondialdehyde, oxypurines, and nucleosides. During ischemia, a time-dependent increase of plasma oxypurines and nucleosides was observed. Plasma malondialdehyde, which was present in minimal amount at zero time (0.058 μmol/liter plasma; SD 0.015), increased after 5 min of ischemia, resulting in a fivefold increase after 30 min of carotid occlusion (0.298 μmol/liter plasma; SD 0.078). Increased plasma malondialdehyde was also recorded in two other groups of animals subjected to the same experimental model, one receiving 20 mg/kg b.w. of the cyclooxygenase inhibitor acetylsalicylate intravenously immediately before ischemia, the other receiving 650 μg/kg b.w. of the hypotensive drug nitroprusside at a flow rate of 103 μl/min intravenously during ischemia, although in this latter group malondialdehyde was significantly higher. The present data indicate that the determination of malondialdehyde, oxypurines, and nucleosides in peripheral blood, may be used to monitor the metabolic alterations of tissues occurring during ischemic phenomena. In addition, these results suggest that the experimental model adopted in the present study induces an incomplete brain ischemia in the rat responsible for the plasma variations of malondialdehyde, oxypurines, and nucleosides, which mainly reflect the consequence of an oxygen radical-mediated tissue injury and an alteration of energy metabolism.